Developing ideas is a 24/7 hobby for them, which might explain why they enjoy one another's company so much.

Tech entrepreneurs C. J. Przybyl and Amanda Thompson keep pretty standard 9-to-5 hours. That is, they return to their Lake Zurich, Illinois, townhouse around 9 each weeknight and then take the Metra back into Chicago at 5 each morning. Whoever gets to the station first in the evening buys beer for the trip, but that hardly means the workday is over—the couple pass time on the train by talking shop.

Przybyl, 29, is chief financial officer of BodyShopBids Inc., a tech startup that raised $1 million in venture capital this month, an investment led by Chicago-based New World Ventures. Thompson, 28, is an account manager at Groupon Inc. Both work at 600 W. Chicago Ave. (BodyShopBids is housed at Lightbank Inc., a tech incubator founded by Groupon co-founders Eric Lefkofsky and Brad Keywell.)

Those aren't necessarily the jobs they discuss on the train. They're just as likely to work on the fledging email-related business that they have undertaken with two partners. In fact, that startup also is likely to occupy their time at home, both during their scarce weeknight hours and on weekends. Neither of them minds a bit.

Many of Chicago's other tech entrepreneurs feel the same way, working long hours and then socializing with other entrepreneurs at venues such as the Motel Bar (in Przybyl's and Thompson's Chicago Avenue building), or Technori Unwind, a Friday afternoon happy hour that changes its location weekly to preserve its secrecy. (It's only for techies.)

The city's tech scene is growing as more prospective entrepreneurs try to replicate the success of local tech companies such as Groupon, GrubHub Inc. and Orbitz Worldwide Inc.

In the old days, "entrepreneurship could be very lonely," according to Seth Kravitz, co-founder of Technori LLC, which publishes an entrepreneurship webzine, and the founder and organizer of the Unwind events. Now that their numbers are reaching critical mass and the allure of launching a startup is reaching fever pitch, tech entrepreneurs "are building a sense of community," Kravitz, 29, says. "We can feel like we're part of something."

A January edition of Unwind at the Paris Club in River North attracted about 60 people, a collection of tech business leaders that was approximately three-fourths male and two-thirds twentysomethings, clustered under a stairwell in their tech-biz uniforms (V-neck sweaters and jeans). The event is supposed to be purely social, with no soliciting allowed and smartphone use discouraged, but neither limit is too realistic for this crowd. For instance, it didn't keep a venture capitalist from inquiring of Przybyl about investing in BodyShopBids without even knowing what the business did.

The line between collaboration, networking and just hanging out is destined to blur at these events because entrepreneurs love talking about building their businesses. Developing ideas is a 24/7 hobby for them, which might explain why they enjoy one another's company so much.

"It's a lifestyle of problem-solving," says Philip Tadros, 32, who owns Chicago-based web-design and creative agency Doejo LLC, as well as several coffee shops where techies congregate, including Noble Tree Cafe in Lincoln Park. (He is launching another, called Bow & Truss, in partnership with Technori's Mr. Kravitz, that is slated to open this spring.)

"My personality is so trained toward launching businesses and solving problems that it's hard to meet somebody and have them not want that," Tadros says.

Tadros, however, has been at the business of entrepreneurship long enough to see value in establishing some boundaries. Where his lifestyle once involved work, grabbing a drink with co-workers, a few hours' sleep and then back to work, he now aims to at least periodically disengage. He says he's found that his projects have benefited as a result.

Entrepreneur Justin Massa, 33, encountered the same sort of crossroads in 2010 when his daughter was born. The CEO of Food Genius Inc., which helps hungry diners find the dishes they crave, knew he would have to give up going out for drinks with fellow techies several nights a week, then heading home to continue working. His solution was perhaps predictable for an entrepreneur: He created Urban Geek Drinks, a monthly meet-up at Villains Bar & Grill in the South Loop for his friends in the tech and public-policy communities. His gatherings average about 80 attendees.

"These are smart people who think very hard on very big problems, and it's fun to talk about how they're solving them," Massa says. "But I'm insanely busy, and I don't have as much time to spend with them as I would like, so I figured I would try to make them come to me."

Massa's shifting priorities aren't unique to tech entrepreneurs. Still, the value he finds in continuing to socialize with techies outside of work is classically entrepreneurial, according to Raman Chadha, executive director of DePaul University's Coleman Entrepreneurship Center.

"Nobody really gets what you're going through as an entrepreneur except other entrepreneurs, and that can be a challenging emotional struggle," he says. Chadha also sees maturity in the breadth of Massa's gatherings: "As entrepreneurs become more seasoned and are running bigger businesses, they start to appreciate the value of different sectors much more."

Sometimes tech entrepreneurs even leave tech to create startups in other sectors. Chuck Templeton still chairs GrubHub's board of directors, but the 43-year-old founder of San Francisco-based restaurant reservation site OpenTable Inc. has turned his entrepreneurial focus toward sustainability issues, launching two websites focused on conservation, OhSoWe.com and Chicago REgen.com, and remodeling his house in hopes of making it energy-neutral. He limits his time away from his wife and two children to one night a week (which, once a month, is devoted to a charity poker game with fellow tech entrepreneurs such as Cleversafe Inc.'s Chris Gladwin and Viewpoints Network LLC's Matt Moog).

Yet, even when Templeton is dining with his family, he has trouble turning off his entrepreneurial impulses.

"I'm constantly evaluating things like, 'Why is this place using wooden chopsticks? Why aren't they using reusable chopsticks?' " he says. "My wife will say, 'Shut up.' I'm way down the extreme on those issues; she's only halfway down, and sometimes it boils over."

Przybyl and Thompson can relate. The difference is that, when it comes to starting businesses, they're both hooked.

"We'll be out to dinner with people, someone will say something, and one of us will get an epiphany," Thompson says. "You look at the other person and ask, 'Has no one thought of this (business idea) yet?' And the wheels start turning. We're a good team, and (the process) is ingrained."

Przybyl and Thompson have known one another since 1999, when both attended high school in suburban Geneva; they have been together since 2002. They're planning to get married, but what comes first, the wedding or the email startup?